Aircraft and other vehicles are being designed to use more subsystems and components that are operated by electrical energy or power. For example more electric motors and actuators are being used and in some instances replacing hydraulic components for operating flight control systems and other systems. Designers are looking for more electrically efficient subsystems and trying to reduce weight and volume of systems while at the same time improving range and optimizing use of energy. The typical electrical switching apparatus used in aircraft use electrical current to provide control signals for switching. Copper signal wiring is fed directly to single devices or to multiple devices packaged into a single module. This wire is subject to degradation and failure of the control signal's quality when exposed to electromagnetic pulse environments. Additionally, the weight of individual copper signal wires with required grounding and shielding running throughout the aircraft for each motor or device needing control can add considerable weight.
Existing designs are heavier, not only for the weight of the wire distribution system, but also clamps and other associated hardware (circuit breakers, etc.) required to support the electrical circuitry for the signal side of the control circuitry. Additionally, where shielding is required to protect against electromagnetic effects even more weight is required. Another issue is that once a system with shielded cables has been put in use, determining if the shields are completely intact can be very challenging. The shields must be completely intact if they are to function properly.
Optical signals are also sometimes used, in a configuration in which the control signals are sent optically close to where they will be used, and then converted into electrical signals by receivers made of photodiodes followed by transimpedance amplifiers. This approach using optical fibers mitigates one electromagnetic vulnerability, but adds a new one. The optical fibers are inherently immune to electromagnetic effects, and so do not require shielding. However, photodiodes are extremely sensitive to radio frequency electromagnetic energy and so must be placed in carefully shielded enclosures. In addition, all entrances to the enclosure, such as for the optical fiber bringing the signal, must be designed to be waveguides-beyond-cutoff for any anticipated frequency of radio frequency energy, and all electric power connections for the photodiode and amplifier must be carefully filtered. Additionally, such photonic control systems require high gain photonic signals. This requires higher powered laser sources for the photonic power. Lasers in these higher power ranges are necessarily larger taking up more volume and are less energy efficient.
Accordingly, there is a need for more electrically efficient subsystems for aircraft and other vehicles that are more resistant to electromagnetic effects and that also have reduced weight and volume to improve range and optimal use of energy.